High-current-density ITO_x/NiO_x thin-film diodes

Thin-film diodes 0.2-4×10-5cm2 in size were fabricated on Al2O3-TiC ceramic substrates from junctions between p-type NiOx and n-type ITOx thin films sputter deposited at ambient temperature. These diodes show a room-temperature turn-on voltage of 0.3-0.6 V and a dc forward current density exceeding 104A/cm2 at an applied voltage of ≃1.5V. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of these diodes can be described by an exponential dependence of I on the applied V and by a linear I/C2 dependence on the reverse applied V, respectively, consistent with those predicted by the various models proposed for the mechanisms for charge-carrier transport in abrupt anisotype heterojunctions. The ideality factor at low-applied V (≤0.3V), the junction built-in potential, and the carrier concentration deduced from these I-V and C-V data are ≃1.5-2, 0.20-0.24 V, and 1.90-1.97×1018/cm3, respectively. © 1998 American Institute of Physics.